1. Field of the Invention
This application is directed to the construction and use of recombinant infectious crustacean and rotifer viruses for the production of peptides and proteins, such as biopharmaceuticals, vaccines, antibodies, enzymes, and hormones, in a crustacean or rotifer.
2. Description of Related Art
The importance of recombinant proteins for modern medical applications and therapy has been pivotal for the rapid advances over the last two decades. Recombinant production methods for bacteria are well developed (Sambrook, Fritsch et al. 1989; Ratledge and Kristiansen 2001). Many proteins are commercially produced in bacterial prokaryotic systems, and have importance in industry and medical science. Recombinant protein production in yeast and other fungi has been extremely well developed both in the laboratory and on a commercial scale (Keranen and Penttila 1995; Archer and Peberdy 1997; Cereghino and Cregg 1999). Due to the requirement for certain types of posttranslational modification for the full and complete function of recombinant proteins in human or animal systems (i.e., glycosylation of the recombinant protein), much of the biopharmaceutical protein production utilizes mammalian cell culture (Ratledge and Kristiansen 2001).
Problems with the production of recombinant proteins using mammalian cell culture (e.g., CHO cells) include the high cost of production and the generally low yield of the recombinant proteins over time, compared to the yields from other single cell systems such as bacteria, yeast, or other fungi. The production of recombinant proteins using insect cells partially overcomes some of these problems, but yields remain relatively low (Goosen 1993).
The production of recombinant proteins in intact insect larvae has provided a potential solution to the high cost of production in insect cell culture (Cha, Dalal et al. 1999). To accomplish this, insect larvae are infected with a modified recombinant virus containing a gene that codes for the expression of a protein of interest. Problems with the insect larval transfection production system include a limited ability to scale up the production of the recombinant proteins, the requirement for purification of the biopharmaceutical, even if it is to be delivered orally, and the fact that the glycosylation pattern of insect-derived biopharmaceuticals is significantly different from that produced by mammalian cell culture. Furthermore, since insects are non-conventional food sources, direct use of their biomass for delivery of recombinant proteins is problematic.
The production of biopharmaceuticals and other recombinant proteins using plant-based systems has been well established (Stoger, Sack et al. 2002). Such a system can be easily scaled up to produce large quantities of the recombinant protein at a relatively low cost. Problems associated with the plant-based expression systems include a long grow-out period, a generally low level of gene expression when transformation is used, a requirement for purification before use even if the product is to be used orally, and a posttranslational modification system that is generally devoid of sialic acid residues (Stoger, Sack et al. 2002).